<!DOCTYPE html>
<html>
  <title>HTML5 Canvas Example</title>

  <style type="text/css">
    @import url("styles.css");
    #heatmap {
        background-image: url("mapbg.jpg");
    }
  </style>

  <h1>HTML5 Canvas Example</h1>
  <p id="support">Your browser supports HTML5 Canvas!</p>
  <h2>Heatmap </h2>
  <canvas id="heatmap" class="clear" style="border: 1px solid ; " height="300" width="300"> </canvas>
    <button id="resetButton">Reset</button>
  

  <script>

    function log() {
        console.log(arguments);
    }

    var points = {};
    var SCALE = 3;

    var x = -1;
    var y = -1;

    function loadDemo() {
        document.getElementById("resetButton").onclick = reset;

        canvas = document.getElementById("heatmap");
        context = canvas.getContext('2d');
        context.globalAlpha = 0.2;
        context.globalCompositeOperation = "lighter";

        function sample() {
            if (x != -1) {
                addToPoint(x,y)
            }
            setTimeout(sample, 100);
        }

        canvas.onmousemove = function(e) {
            x = e.clientX - e.target.offsetLeft;
            y = e.clientY - e.target.offsetTop;
            addToPoint(x,y)
        }

        sample();
    }

    function reset() {
        points = {};
        context.clearRect(0,0,300,300);
        x = -1;
        y = -1;
    }


    function getColor(intensity) {
        var colors = ["#072933", "#2E4045", "#8C593B", "#B2814E", "#FAC268", "#FAD237"];
        return colors[Math.floor(intensity/2)];
    }

    function drawPoint(x, y, radius) {
            context.fillStyle= getColor(radius);
            radius = Math.sqrt(radius)*6;

            context.beginPath();
            context.arc(x, y, radius, 0, Math.PI*2, true)

            context.closePath();
            context.fill();
    }

    function addToPoint(x, y) {
        x = Math.floor(x/SCALE);
        y= Math.floor(y/SCALE);

        if (!points[[x,y]]) {
            points[[x,y]] = 1;
        } else if (points[[x,y]]==10) {
return
        } else {
            points[[x,y]]++;
        }
        drawPoint(x*SCALE,y*SCALE, points[[x,y]]);
    }


    window.addEventListener("load", loadDemo, true);
  </script>
</html>

